Habsburg Secundogeniture
However, Francis V had decided to retain the Este name in the Habsburg family, and left most of his huge estate to his young cousin Archduke Franz Ferdinand of Austria, with certain conditions, one of which is that the heir and future heirs use the name of Este. The tradition of Este family thus fell to the line of Archduke Charles Louis, younger brother to then Emperor Francis Joseph, Austria-Este then becoming a sort of "secundogeniture" title within the Austrian imperial family.
As explained, the first "adoptee" was Archduke Franz Ferdinand (b. 1863 and not descended from Mary Beatrice d'Este), who took the name Austria-Este, and also in 1896 became the heir presumptive of the Austrian Empire, but was murdered 28 June 1914 in Sarajevo. Since his own children were born in morganatic marriage (see House of Hohenberg), the Habsburgs designated his soon-to-be born great-nephew Robert (born 8 February 1915), second son of the future emperor Charles, as the next "adopted Austria-Este". Through his mother Zita of Parma (a great-granddaughter of Teresa of Savoy, Duchess of Lucca and Parma, who was daughter of Teresa of Modena, Queen of Sardinia, who was daughter of Mary Beatrice d'Este and Ferdinand of Austria, Duchess and Duke of Breisgau and Modena), Archduke Robert happened to be a descendant of Duke Ercole III d'Este as well, and thus the blood of last Este dukes joined with the name Austria-Este.
Read more about this topic: Austria-Este